Documentation is key
If you have separate documentation for both visits, I'd bill both and append modifier 25 to the second.
That being said, I assume you will have separate diagnoses. The first should be for the symptoms prompting the CT, the second should be the definitive diagnosis as a result of the CT.
You should bill these claims together, on a paper claim form, with a brief explanation of the separateness and documentation of both encounters attached. You may have to appeal a decision to rebundle the claims, but you should win if you try. You may want to direct the claims to your provider representative right off the bat if they are willling to accept it; they can be very helpful in these rare, sticky situations.